Low RPM oil flow issues in diesel engines can stem from various factors, including the type of engine and the specific oil being used. It's crucial to clarify whether the concern is about lubricating oil or fuel oil, as this impacts troubleshooting steps. Observing oil flow in a sight glass can help diagnose the problem, as a lack of visible flow may indicate a blockage or pump failure. Additional details about the engine type, whether it's in a car, truck, or ship, are necessary for accurate troubleshooting. Proper identification of the issue is essential for effective resolution.